The Java.util.Stack.insertElementAt(element, index) method is used to insert a particular element at the specified index of the Stack. Both the element and the position is passed as the parameters. If an element is inserted at a specified index, then all the elements are pushed upward by one and hence the capacity is increased, creating a space for the new element.
Syntax:Â
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Stack.insertElementAt()
Parameters: The method accepts two parameters:Â
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- element: This is element required to be inserted into the Stack.
- index: This is of integer type and refers to the position where the new element is to be inserted.
Return Value: The method does not return anything.
Exception: The method throws ArrayIndexOutOfBoundsException if the index is an invalid number.
Below programs illustrate the Java.util.Stack.insertElementAt() method:
Program 1: Adding String elements into the Stack.
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Java
// Java code to illustrate insertElementAt()import java.util.*;Â
public class StackDemo {    public static void main(String args[])    {        // Creating an empty Stack        Stack<String> stack = new Stack<String>();Â
        // Use add() method to add elements into the Stack        stack.add("Welcome");        stack.add("To");        stack.add("Geeks");        stack.add("4");        stack.add("Geeks");Â
        // Displaying the Stack        System.out.println("Stack: " + stack);Â
        // Inserting element at 3rd position        stack.insertElementAt("Hello", 2);Â
        // Inserting element at last position        stack.insertElementAt("World", 6);Â
        // Displaying the final Stack        System.out.println("The final Stack is "                           + stack);    }} |
Stack: [Welcome, To, Geeks, 4, Geeks] The final Stack is [Welcome, To, Hello, Geeks, 4, Geeks, World]
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Program 2: Adding Integer elements into the Stack.Â
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Java
// Java code to illustrate insertElementAt()import java.util.*;Â
public class StackDemo {    public static void main(String args[])    {        // Creating an empty Stack        Stack<Integer> stack = new Stack<Integer>();Â
        // Use add() method to add elements into the Stack        stack.add(10);        stack.add(20);        stack.add(30);        stack.add(40);        stack.add(50);Â
        // Displaying the Stack        System.out.println("Stack: " + stack);Â
        // Inserting element at 1st position        stack.insertElementAt(100, 0);Â
        // Inserting element at fifth position        stack.insertElementAt(200, 4);Â
        // Displaying the final Stack        System.out.println("The final Stack is "                           + stack);    }} |
Stack: [10, 20, 30, 40, 50] The final Stack is [100, 10, 20, 30, 200, 40, 50]
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